--- a/src/HOL/Extraction.thy Sun Jan 06 13:44:33 2019 +0100
+++ b/src/HOL/Extraction.thy Sun Jan 06 15:04:34 2019 +0100
@@ -8,7 +8,7 @@
imports Option
begin
-ML_file "Tools/rewrite_hol_proof.ML"
+ML_file \<open>Tools/rewrite_hol_proof.ML\<close>
subsection \<open>Setup\<close>